Is there any limitation in R.E.D. Server and why?
R.E.D. Server has been developed to derive RESP or ESP charge values embedded in force field library(ies) for small molecules and/or molecular fragments. It is not designed to handle large molecular systems such as a polypeptide, a polynucleotide or a polysaccharide. Consequently, the maximum number of atoms for a molecule/conformation in an input file handled by R.E.D. Server is set to 150 atoms. However, this does not mean R.E.D. Server cannot be used to derive RESP or ESP charges and build force field library(ies) for larger molecular systems. In this case, a user only needs to split a “big” molecule/polymer into elementary building blocks with fully defined conformation(s) and use specific constraints during the charge fitting step to reconstruct the initial/big molecule. See the Tutorials related the R.E.D. Tools, R.E.DD.B. and R.E.D. Server for more information about the derivation of RESP or ESP charge values and the building of force field library(ies) for small molecules and/o
